This patch is for linux-6.1.y and earlier, it has no direct mainline equivalent.

In order to backport commit d5c8d6e0fa61 ("kbuild: Update assembler calls to use proper flags and language target") to resolve a separate issue regarding PowerPC, the problem noticed and fixed by commit 80a20d2f8288 ("MIPS: Always use -Wa,-msoft-float and eliminate GAS_HAS_SET_HARDFLOAT") needs to be addressed. Unfortunately, 6.1 and earlier do not contain commit e4412739472b ("Documentation: raise minimum supported version of binutils to 2.25"), so it cannot be assumed that all supported versions of GNU as have support for -msoft-float.

In order to switch from KBUILD_CFLAGS to KBUILD_AFLAGS in as-option without consequence, move the '-Wa,-msoft-float' check to cc-option, including '$(cflags-y)' directly to avoid the issue mentioned in commit 80a20d2f8288 ("MIPS: Always use -Wa,-msoft-float and eliminate GAS_HAS_SET_HARDFLOAT").

Signed-off-by: Nathan Chancellor nathan@kernel.org --- Cc: tsbogend@alpha.franken.de Cc: linux-mips@vger.kernel.org --- arch/mips/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/mips/Makefile b/arch/mips/Makefile index b296e33f8e33..de8d508f27af 100644 --- a/arch/mips/Makefile +++ b/arch/mips/Makefile @@ -109,7 +109,7 @@ endif # (specifically newer than 2.24.51.20140728) we then also need to explicitly # set ".set hardfloat" in all files which manipulate floating point registers. # -ifneq ($(call as-option,-Wa$(comma)-msoft-float,),) +ifneq ($(call cc-option,$(cflags-y) -Wa$(comma)-msoft-float,),) cflags-y += -DGAS_HAS_SET_HARDFLOAT -Wa,-msoft-float endif

From: Nick Desaulniers ndesaulniers@google.com

commit d5c8d6e0fa61401a729e9eb6a9c7077b2d3aebb0 upstream.

as-instr uses KBUILD_AFLAGS, but as-option uses KBUILD_CFLAGS. This can cause as-option to fail unexpectedly when CONFIG_WERROR is set, because clang will emit -Werror,-Wunused-command-line-argument for various -m and -f flags in KBUILD_CFLAGS for assembler sources.

Callers of as-option and as-instr should be adding flags to KBUILD_AFLAGS / aflags-y, not KBUILD_CFLAGS / cflags-y. Use KBUILD_AFLAGS in all macros to clear up the initial problem.

Unfortunately, -Wunused-command-line-argument can still be triggered with clang by the presence of warning flags or macro definitions because '-x assembler' is used, instead of '-x assembler-with-cpp', which will consume these flags. Switch to '-x assembler-with-cpp' in places where '-x assembler' is used, as the compiler is always used as the driver for out of line assembler sources in the kernel.

Finally, add -Werror to these macros so that they behave consistently whether or not CONFIG_WERROR is set.

[nathan: Reworded and expanded on problems in commit message Use '-x assembler-with-cpp' in a couple more places]

Link: https://github.com/ClangBuiltLinux/linux/issues/1699 Suggested-by: Masahiro Yamada masahiroy@kernel.org Signed-off-by: Nick Desaulniers ndesaulniers@google.com Signed-off-by: Nathan Chancellor nathan@kernel.org Tested-by: Linux Kernel Functional Testing lkft@linaro.org Tested-by: Anders Roxell anders.roxell@linaro.org Signed-off-by: Masahiro Yamada masahiroy@kernel.org Signed-off-by: Nathan Chancellor nathan@kernel.org --- scripts/Kconfig.include | 2 +- scripts/Makefile.compiler | 8 ++++---- scripts/as-version.sh | 2 +- 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include index 274125307ebd..5a84b6443875 100644 --- a/scripts/Kconfig.include +++ b/scripts/Kconfig.include @@ -33,7 +33,7 @@ ld-option = $(success,$(LD) -v $(1))

# $(as-instr,<instr>) # Return y if the assembler supports <instr>, n otherwise -as-instr = $(success,printf "%b\n" "$(1)" | $(CC) $(CLANG_FLAGS) -c -x assembler -o /dev/null -) +as-instr = $(success,printf "%b\n" "$(1)" | $(CC) $(CLANG_FLAGS) -c -x assembler-with-cpp -o /dev/null -)

# check if $(CC) and $(LD) exist $(error-if,$(failure,command -v $(CC)),C compiler '$(CC)' not found) diff --git a/scripts/Makefile.compiler b/scripts/Makefile.compiler index 20d353dcabfb..158c57f2acfd 100644 --- a/scripts/Makefile.compiler +++ b/scripts/Makefile.compiler @@ -29,16 +29,16 @@ try-run = $(shell set -e; \ fi)

# as-option -# Usage: cflags-y += $(call as-option,-Wa$(comma)-isa=foo,) +# Usage: aflags-y += $(call as-option,-Wa$(comma)-isa=foo,)

as-option = $(call try-run,\ - $(CC) $(KBUILD_CFLAGS) $(1) -c -x assembler /dev/null -o "$$TMP",$(1),$(2)) + $(CC) -Werror $(KBUILD_AFLAGS) $(1) -c -x assembler-with-cpp /dev/null -o "$$TMP",$(1),$(2))

# as-instr -# Usage: cflags-y += $(call as-instr,instr,option1,option2) +# Usage: aflags-y += $(call as-instr,instr,option1,option2)

as-instr = $(call try-run,\ - printf "%b\n" "$(1)" | $(CC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" -,$(2),$(3)) + printf "%b\n" "$(1)" | $(CC) -Werror $(KBUILD_AFLAGS) -c -x assembler-with-cpp -o "$$TMP" -,$(2),$(3))

# __cc-option # Usage: MY_CFLAGS += $(call __cc-option,$(CC),$(MY_CFLAGS),-march=winchip-c6,-march=i586) diff --git a/scripts/as-version.sh b/scripts/as-version.sh index 1a21495e9ff0..af717476152d 100755 --- a/scripts/as-version.sh +++ b/scripts/as-version.sh @@ -45,7 +45,7 @@ orig_args="$@" # Get the first line of the --version output. IFS=' ' -set -- $(LC_ALL=C "$@" -Wa,--version -c -x assembler /dev/null -o /dev/null 2>/dev/null) +set -- $(LC_ALL=C "$@" -Wa,--version -c -x assembler-with-cpp /dev/null -o /dev/null 2>/dev/null)

# Split the line on spaces. IFS=' '